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Multi-stability of circadian phase wave within early postnatal suprachiasmatic nucleus.

Jeong B, Hong JH, Kim H, Choe HK, Kim K, Lee KJ - Sci Rep (2016)

Bottom Line: Here, we show that this is not the case in early postnatal SCN.Furthermore, mode transitions can be induced by a pulse of 38.5 °C temperature perturbation.These results lead to new important questions of what the observed multi-stability means for the proper function of an SCN and its arrhythmia.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Korea University, Seoul, 136-713, Korea.

ABSTRACT
The suprachiasmatic nucleus (SCN) is a group of cells that functions as a biological master clock. In different SCN cells, oscillations of biochemical markers such as the expression-level of clock genes, are not synchronized but instead form slow circadian phase waves propagating over the whole cell population spatio-temporal structure is a fixed property set by the anatomy of a given SCN. Here, we show that this is not the case in early postnatal SCN. Earlier studies presumed that their Based on bioluminescence imaging experiments with Per2-Luciferase mice SCN cultures which guided computer simulations of a realistic model of the SCN, we demonstrate that the wave is not unique but can be in various modes including phase- coherent oscillation, crescent-shaped wave, and most notably, a rotating pinwheel wave that conceptually resembles a wall clock with a rotating hand. Furthermore, mode transitions can be induced by a pulse of 38.5 °C temperature perturbation. Importantly, the waves support a significantly different period, suggesting that neither a spatially-fixed phase ordering nor a specialized pacemaker having a fixed period exist in these studied SCNs. These results lead to new important questions of what the observed multi-stability means for the proper function of an SCN and its arrhythmia.

No MeSH data available.


Related in: MedlinePlus

Multi-stability of the SCN phase wave rendered visible by temperature perturbations.(a) An oval shaped wave converging toward the middle of the nucleus. (b) A complex state having several fragmented domains oscillating out-of-phase to each other. ( = 507μm) (c) An almost globally in-phase oscillation. (d) One dimensional space () vs. time plot showing the formation of phase bubbles. (e) Two local time series oscillating anti-phase to each other: one obtained inside a phase bubble [location marked by a gray dot in (b, 0 h)] and the other just outside the bubble [black dot in (b, 0 h)]. (f) The histograms illustrating the difference in the degree of phase dispersal of the three different states, shown in (a), (b) and (c), respectively.
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f3: Multi-stability of the SCN phase wave rendered visible by temperature perturbations.(a) An oval shaped wave converging toward the middle of the nucleus. (b) A complex state having several fragmented domains oscillating out-of-phase to each other. ( = 507μm) (c) An almost globally in-phase oscillation. (d) One dimensional space () vs. time plot showing the formation of phase bubbles. (e) Two local time series oscillating anti-phase to each other: one obtained inside a phase bubble [location marked by a gray dot in (b, 0 h)] and the other just outside the bubble [black dot in (b, 0 h)]. (f) The histograms illustrating the difference in the degree of phase dispersal of the three different states, shown in (a), (b) and (c), respectively.

Mentions: Shown in Fig. 3 is yet another type of SCN phase wave. A different SCN sample was monitored to support, more or less, an oval-shaped wave initially (Fig. 3a). Approximately, the wave started out from the perimeter of the SCN and traveled toward the central region, and the convergence is evident in the 1D space-time plot of Fig. 3d (day 0 ~ 3) as well as in Fig. 3a. We then applied a temperature perturbation, again when the range of phase dispersal was believed to include the unstable fixed point of the sample’s PRC. This time, instead of a pinwheel, the system produced several fragmented domains, some of which were oscillating almost completely out of phase with respect to its neighbor as shown in Fig. 3b,d,e (see Supplementary Movie 2) (similar dynamic domain structures were termed as “the phase bubbles” in3233): Consequently, the phase dispersal in space almost became full coverage of the 2π range [see Fig. 3f (turbulent)] from the initial, narrower distribution [Fig. 3f (oval)]. Under the same (or similar) condition, phase bubbles were more popularly created (6 times out of 8 attempts, based on 6 different slices from six 6 different animals) than phase singularities (2 times out of 8 attempts). Unlike the case of the rotating pinwheel which also covers a full 2π range in space, however, the new complex state having phase bubbles was globally unstable and transformed to an almost phase-synchronized state as shown in Fig. 3c,f (homogeneous): in Fig. 3d, one shrinking phase bubble is delineated by a pair of black dashed lines. The transition had taken place by a rather abrupt disappearance of phase bubbles during day 7 ~ 8 (see Fig. 3d). The newly established phase-synchronized state was stable even after another perturbation was delivered (between day 9 and day 10).


Multi-stability of circadian phase wave within early postnatal suprachiasmatic nucleus.

Jeong B, Hong JH, Kim H, Choe HK, Kim K, Lee KJ - Sci Rep (2016)

Multi-stability of the SCN phase wave rendered visible by temperature perturbations.(a) An oval shaped wave converging toward the middle of the nucleus. (b) A complex state having several fragmented domains oscillating out-of-phase to each other. ( = 507μm) (c) An almost globally in-phase oscillation. (d) One dimensional space () vs. time plot showing the formation of phase bubbles. (e) Two local time series oscillating anti-phase to each other: one obtained inside a phase bubble [location marked by a gray dot in (b, 0 h)] and the other just outside the bubble [black dot in (b, 0 h)]. (f) The histograms illustrating the difference in the degree of phase dispersal of the three different states, shown in (a), (b) and (c), respectively.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4759822&req=5

f3: Multi-stability of the SCN phase wave rendered visible by temperature perturbations.(a) An oval shaped wave converging toward the middle of the nucleus. (b) A complex state having several fragmented domains oscillating out-of-phase to each other. ( = 507μm) (c) An almost globally in-phase oscillation. (d) One dimensional space () vs. time plot showing the formation of phase bubbles. (e) Two local time series oscillating anti-phase to each other: one obtained inside a phase bubble [location marked by a gray dot in (b, 0 h)] and the other just outside the bubble [black dot in (b, 0 h)]. (f) The histograms illustrating the difference in the degree of phase dispersal of the three different states, shown in (a), (b) and (c), respectively.
Mentions: Shown in Fig. 3 is yet another type of SCN phase wave. A different SCN sample was monitored to support, more or less, an oval-shaped wave initially (Fig. 3a). Approximately, the wave started out from the perimeter of the SCN and traveled toward the central region, and the convergence is evident in the 1D space-time plot of Fig. 3d (day 0 ~ 3) as well as in Fig. 3a. We then applied a temperature perturbation, again when the range of phase dispersal was believed to include the unstable fixed point of the sample’s PRC. This time, instead of a pinwheel, the system produced several fragmented domains, some of which were oscillating almost completely out of phase with respect to its neighbor as shown in Fig. 3b,d,e (see Supplementary Movie 2) (similar dynamic domain structures were termed as “the phase bubbles” in3233): Consequently, the phase dispersal in space almost became full coverage of the 2π range [see Fig. 3f (turbulent)] from the initial, narrower distribution [Fig. 3f (oval)]. Under the same (or similar) condition, phase bubbles were more popularly created (6 times out of 8 attempts, based on 6 different slices from six 6 different animals) than phase singularities (2 times out of 8 attempts). Unlike the case of the rotating pinwheel which also covers a full 2π range in space, however, the new complex state having phase bubbles was globally unstable and transformed to an almost phase-synchronized state as shown in Fig. 3c,f (homogeneous): in Fig. 3d, one shrinking phase bubble is delineated by a pair of black dashed lines. The transition had taken place by a rather abrupt disappearance of phase bubbles during day 7 ~ 8 (see Fig. 3d). The newly established phase-synchronized state was stable even after another perturbation was delivered (between day 9 and day 10).

Bottom Line: Here, we show that this is not the case in early postnatal SCN.Furthermore, mode transitions can be induced by a pulse of 38.5 °C temperature perturbation.These results lead to new important questions of what the observed multi-stability means for the proper function of an SCN and its arrhythmia.

View Article: PubMed Central - PubMed

Affiliation: Department of Physics, Korea University, Seoul, 136-713, Korea.

ABSTRACT
The suprachiasmatic nucleus (SCN) is a group of cells that functions as a biological master clock. In different SCN cells, oscillations of biochemical markers such as the expression-level of clock genes, are not synchronized but instead form slow circadian phase waves propagating over the whole cell population spatio-temporal structure is a fixed property set by the anatomy of a given SCN. Here, we show that this is not the case in early postnatal SCN. Earlier studies presumed that their Based on bioluminescence imaging experiments with Per2-Luciferase mice SCN cultures which guided computer simulations of a realistic model of the SCN, we demonstrate that the wave is not unique but can be in various modes including phase- coherent oscillation, crescent-shaped wave, and most notably, a rotating pinwheel wave that conceptually resembles a wall clock with a rotating hand. Furthermore, mode transitions can be induced by a pulse of 38.5 °C temperature perturbation. Importantly, the waves support a significantly different period, suggesting that neither a spatially-fixed phase ordering nor a specialized pacemaker having a fixed period exist in these studied SCNs. These results lead to new important questions of what the observed multi-stability means for the proper function of an SCN and its arrhythmia.

No MeSH data available.


Related in: MedlinePlus